For 5 years, we have been exploring the use of self-assembly and templating to create metal nanostructures which have strong structural colour resonances [1]. These depend on light trapped near the surface of 3D sculpted noble metals on size scales from 100 nm to 10 μm. We have also been developing self-assembled plastic photonic crystals for structural colour applications.[2] Also, we have been developing spherical microcavities like these to demonstrate resonant trapping of specific colours of light [3].
The present invention combines these three ideas together to make metal structures embedded in elastic films, whose colour changes when stretched.